The Palaeo Times News

Total Page:16

File Type:pdf, Size:1020Kb

The Palaeo Times News 11TH JuNE 2020 13TH JuNE 2020 LATEST LATEST FOSSIL FOSSIL NEWS THE PALAEO TIMES NEWS [email protected] CONFErENCE EdITION @CharlotteMBird BRAINTEASERS: EVOLUTION AND VARIATION IN CYNODONT ENDOCRANIAL ANATOMY Charlotte M. Bird1,2, Stephan Lautenschlager1, Paul M. Barrett2 PEERING INSIDE THE SKULL 1 School of Geography, Earth and Environmental Sciences, University of Birmingham, UK 2 Department of Earth Sciences, Natural History Museum, London, UK New anatomical descriptions of the Thrinaxodon brain and inner ear highlight structurally similar endocranial anatomy across all cynodonts studied, with a foramen magnum, cerebellum, paraflocculi, cerebral hemispheres and olfactory bulbs (figure 1). Cloud Compare analyses of the Thrinaxodon models (figure 3) shows millimeter scale size variations amongst the reconstructed elements, alongside slight shape changes in the olfactory region (figure 4). Figure 3. Digital endocast summary of the three studied With the three Thrinaxodon Thrinaxodon liorhinus specimens. specimens all being at various stages of adulthood, this indicates the potential for identifying intraspecific variation. Cerebellum However, the variation is not Cerebral hemispheres significant enough to make a Foramen definitive conclusion as to magnum Figure 1. CT scan of a Thrinaxodon skull (length 74mm) whether the changes result from and associated reconstructed endocranial anatomy subjectivity during the model (brain – blue, length 35mm; inner ear – yellow; neurovascular structures – red). making process or are natural Figure 4. CloudCompare analyses reveal intraspecific variations. It is thus necessary to differences in the olfactory bulbs (blue) for specimens UMZC produce further models for this T815 and NHM 511 respectively. Olfactory bulbs species for a plethora of skull sizes to assess the presence of Paraflocculi ontogenetic variation. Calculated encephalisation quotients for Thrinaxodon vary between 0.15 and 0.2, consistent Using 3D reconstruction techniques to investigate with other, more derived cynodonts (figure 5). However, a cognitive change accompanies the origination of Mammaliaformes, with EQ values between 0.5 and 1.09 for Monodelphis, intraspecific and ontogenetic variation within suggesting a more primitive cognitive ability for Thrinaxodon, despite a similar body size. endocranial structures, quantifying relative Regarding inner ear anatomy, Thrinaxodon possessed larger semi-circular canals than later cynodonts (for example, Brasilitherium). With these canals being responsible for coordination cognition, sensory capabilities and anatomical and agility (by detecting angular accelerations and decelerations in the head), it may be that evolution along the cynodont-mammal lineage. inner ear anatomy was a strong influence upon Thrinaxodon being able to hunt successfully. Moreover, calculation of a best hearing frequency between 1.87 and 2.41 kHz for Thrinaxodon is considerably more restricted than in Monodelphis domestica (8 to 64 kHz; Frost and Masterton 1994). Consequently, Thrinaxodon’s poor auditory acuity may have been compensated for by larger olfactory bulbs than in later cynodont genera, thus ONCE UPON A TIME... supporting a burrowing life mode and nocturnal hunting style. Fossils had to be destroyed to make a model of the brain, but thankfully virtual palaeontology has come to the rescue, utilising non-destructive modeling techniques to restore soft tissues lost to time. Such methods are of particular interest for the understudied Cynodontia, a group of therapsids that survived the end-Permian extinction event to radiate during the Triassic, with later Mammalian origination. Cynodont brains are yet to be comprehensively studied for morphological evolution and as such, no known attempts have been made to identify intraspecific (between members of a species), ontogenetic (life cycle) and sexually dimorphic variation. With Thrinaxodon liorhinus exhibiting the most abundant cynodont fossil record, it thus facilitates study of brain, inner ear and neurovascular anatomy (figure 1) to identify these changes and permits further understanding of the evolution of sensory capabilities and subsequent behavioural patterns. Moreover, the methodology provides opportunity to discover biases in digital reconstruction techniques resulting from the software used and the subjectivity of the model maker. PAINTING THE PAST High resolution CT scans of cynodont skulls facilitate 3D endocranial reconstruction within Figure 5. The evolutionary development of mammalian brain morphology, highlighting cognitive compartmentalisation from the late Avizo (and comparative software, including SPIERS, VG Studio and Mimics). Linear and Permian onwards. volumetric analyses within Avizo and CloudCompare assess size and shape changes for individual parts of the brain and inner ear, with calculation of encephalisation quotients (a measure of relative cognitive ability) and best hearing frequencies possible for comparison with more recent cynodont genera and the modern Monodelphis domestica (figure 2). CONCLUSIONS REFERENCES Frost, S.B. & Masterton, R.B. 1994. Hearing in primitive The lack of basicranial bones in mammals: Monodelphis domestica and Marmosa elegans. the braincase and subjectivity Hearing Research, 76, 67–72. during the modelling process Brasilitherium riograndensis Macrini, T.E., Rowe, T. & VandeBerg, J.L. 2007. Cranial Thrinaxodon liorhinus UFRGS-PV-1043-T pose some of the greatest Endocasts from a Growth Series of Monodelphis domestica NHMUK PV R 511 (Rodrigues et al. 2014) (Didelphidae, Marsupialia): A Study of Individual and Riograndia guaibensis challenges to studying cynodont UFRGS-PV-596-T Ontogenetic Variation. Journal of Morphology, 268, 844–865. (Rodrigues et al. 2018) endocranial anatomy. Yet analysing a larger dataset of Rodrigues, P.G., Ruf, I. & Schultz, C.L. 2014. Study of a digital cranial endocast of the non-mammaliaform cynodont skulls over a plethora of size Brasilitherium riograndensis (Later Triassic, Brazil) and its Thrinaxodon liorhinus Monodelphis domestica ranges and temporal relevance to the evolution of the mammalian brain. UMZC T815 Figure 2. Sample of the TMM M-7599 Paläontologische Zeitschrift, 88, 329–352. (Macrini et al. 2007) distributions will provide new species studied insights into the evolution of the Rodrigues, P.G., Martinelli, A.G., Schultz, C.L., Corfe, I.J., Gill, mammalian brain from its P.G, Soares, M.B. et al. 2018. Digital cranial endocast of ancestral forebears. Riograndia guaibensis (Late Triassic, Brazil) sheds light on the evolution of the brain in non-mammalian cynodonts, Historical Biology, 1–18..
Recommended publications
  • Reptile-Like Physiology in Early Jurassic Stem-Mammals
    bioRxiv preprint doi: https://doi.org/10.1101/785360; this version posted October 10, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Title: Reptile-like physiology in Early Jurassic stem-mammals Authors: Elis Newham1*, Pamela G. Gill2,3*, Philippa Brewer3, Michael J. Benton2, Vincent Fernandez4,5, Neil J. Gostling6, David Haberthür7, Jukka Jernvall8, Tuomas Kankanpää9, Aki 5 Kallonen10, Charles Navarro2, Alexandra Pacureanu5, Berit Zeller-Plumhoff11, Kelly Richards12, Kate Robson-Brown13, Philipp Schneider14, Heikki Suhonen10, Paul Tafforeau5, Katherine Williams14, & Ian J. Corfe8*. Affiliations: 10 1School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, UK. 2School of Earth Sciences, University of Bristol, Bristol, UK. 3Earth Science Department, The Natural History Museum, London, UK. 4Core Research Laboratories, The Natural History Museum, London, UK. 5European Synchrotron Radiation Facility, Grenoble, France. 15 6School of Biological Sciences, University of Southampton, Southampton, UK. 7Institute of Anatomy, University of Bern, Bern, Switzerland. 8Institute of Biotechnology, University of Helsinki, Helsinki, Finland. 9Department of Agricultural Sciences, University of Helsinki, Helsinki, Finland. 10Department of Physics, University of Helsinki, Helsinki, Finland. 20 11Helmholtz-Zentrum Geesthacht, Zentrum für Material-und Küstenforschung GmbH Germany. 12Oxford University Museum of Natural History, Oxford, OX1 3PW, UK. 1 bioRxiv preprint doi: https://doi.org/10.1101/785360; this version posted October 10, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. 13Department of Anthropology and Archaeology, University of Bristol, Bristol, UK. 14Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, UK.
    [Show full text]
  • Micheli Stefanello
    UNIVERSIDADE FEDERAL DE SANTA MARIA CENTRO DE CIÊNCIAS NATURAIS E EXATAS PROGRAMA DE PÓS-GRADUAÇÃO EM BIODIVERSIDADE ANIMAL Micheli Stefanello DESCRIÇÃO E FILOGENIA DE UM NOVO ESPÉCIME DE CINODONTE PROBAINOGNÁTIO DO TRIÁSSICO SUL-BRASILEIRO Santa Maria, RS 2018 Micheli Stefanello DESCRIÇÃO E FILOGENIA DE UM NOVO ESPÉCIME DE CINODONTE PROBAINOGNÁTIO DO TRIÁSSICO SUL-BRASILEIRO Dissertação apresentada ao Curso de Mestrado do Programa de Pós-Graduação em Biodiversidade Animal, Área de Concentração em Sistemática e Biologia Evolutiva, da Universidade Federal de Santa Maria (UFSM, RS), como requisito parcial para obtenção do grau de Mestre em Ciências Biológicas – Área Biodiversidade Animal. Orientador: Prof. Dr. Sérgio Dias da Silva Santa Maria, RS 2018 Micheli Stefanello DESCRIÇÃO E FILOGENIA DE UM NOVO ESPÉCIME DE CINODONTE PROBAINOGNÁTIO DO TRIÁSSICO SUL-BRASILEIRO Dissertação apresentada ao Curso de Mestrado do Programa de Pós-Graduação em Biodiversidade Animal, Área de Concentração em Sistemática e Biologia Evolutiva, da Universidade Federal de Santa Maria (UFSM, RS), como requisito parcial para obtenção do grau de Mestre em Ciências Biológicas – Área Biodiversidade Animal. Aprovada em 28 de fevereiro de 2018: Santa Maria, RS 2018 AGRADECIMENTOS Ao meu orientador, Dr. Sérgio Dias da Silva, pela orientação, por todo o tempo despendido ao longo desse mestrado e por possibilitar meu aprimoramento na área a qual tenho apreço. Aos colegas do Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia da Universidade Federal de Santa Maria (CAPPA/UFSM) e do Laboratório de Paleobiodiversidade Triássica, dessa mesma instituição, pela convivência e por terem ajudado-me de diferentes formas ao longo do mestrado. Em especial, ao colega Rodrigo Temp Müller, pela coleta do espécime (objeto de estudo dessa dissertação), por toda a ajuda com o TNT e com as figuras, e por auxiliar-me de inúmeras formas.
    [Show full text]
  • Studies on Continental Late Triassic Tetrapod Biochronology. I. the Type Locality of Saturnalia Tupiniquim and the Faunal Succession in South Brazil
    Journal of South American Earth Sciences 19 (2005) 205–218 www.elsevier.com/locate/jsames Studies on continental Late Triassic tetrapod biochronology. I. The type locality of Saturnalia tupiniquim and the faunal succession in south Brazil Max Cardoso Langer* Departamento de Biologia, FFCLRP, Universidade de Sa˜o Paulo (USP), Av. Bandeirantes 3900, 14040-901 Ribeira˜o Preto, SP, Brazil Received 1 November 2003; accepted 1 January 2005 Abstract Late Triassic deposits of the Parana´ Basin, Rio Grande do Sul, Brazil, encompass a single third-order, tetrapod-bearing sedimentary sequence that includes parts of the Alemoa Member (Santa Maria Formation) and the Caturrita Formation. A rich, diverse succession of terrestrial tetrapod communities is recorded in these sediments, which can be divided into at least three faunal associations. The stem- sauropodomorph Saturnalia tupiniquim was collected in the locality known as ‘Waldsanga’ near the city of Santa Maria. In that area, the deposits of the Alemoa Member yield the ‘Alemoa local fauna,’ which typifies the first association; includes the rhynchosaur Hyperodapedon, aetosaurs, and basal dinosaurs; and is coeval with the lower fauna of the Ischigualasto Formation, Bermejo Basin, NW Argentina. The second association is recorded in deposits of both the Alemoa Member and the Caturrita Formation, characterized by the rhynchosaur ‘Scaphonyx’ sulcognathus and the cynodont Exaeretodon, and correlated with the upper fauna of the Ischigualasto Formation. Various isolated outcrops of the Caturrita Formation yield tetrapod fossils that correspond to post-Ischigualastian faunas but might not belong to a single faunal association. The record of the dicynodont Jachaleria suggests correlations with the lower part of the Los Colorados Formation, NW Argentina, whereas remains of derived tritheledontid cynodonts indicate younger ages.
    [Show full text]
  • Mammalian Origins Major Groups of Synapsida
    Mammalogy 4764 9/16/2009 Chapter 4 “Reptile” Mammalian Origins Early mammal Carnivore Amniota Herbivore Feldhamer Table 4.1 Savage and Long 1986 Major Fig. 3.2, Vaughn, Fig. 4.1, Feldhamer groups Mammalian Origins of Dimetrodon Overview Synapsida Synapsids Pelycosaurs and Therapsids First Mammals Mesozoic Era appear Feldhamer Fig. 4.2 Cenozoic Era radiate Savage and Long 1986 Pelycosaur Skull, jaw musculature, and teeth Cynodontia -- Advanced, predaceous therapsids Pelycosaur Scymnognathus Cynognathus Therapsid Early Cynodont Derived Therapsid/Mammal Primitive Late Cynodont Fig. 3.2, Vaughn Thrinaxodon Fig 4.3 & 4, Feldhamer 1 Mammalogy 4764 9/16/2009 Skeletal transition Extinction of Cynodonts Possibly competition from dinosaurs Pelycosaur Early Cynodonts were dog-size, last surviving were squirrel sized Fig. 4.15 Mammals that survived while Cynodonts went extinct (contemporary) were mouse-sized. Cynodont Thrinaxodon Modern Mammal Fig. 3.5, Vaughn Fig. 4.16c, Early Cynodont Early mammals Changes in land masses Feldhamer 4.11 200 - 250 million years ago Derived characters: Dentary/squamosal jaw articulation Diphyodont dentition 200 MYA 180 MYA Mammary glands Secondary palate Early Mid- Viviparity (loss of eggshell) When? Jurassic Jurassic 65 MYA 135 MYA Early Early Cretaceous Cenozoic Feldhamer 4.5, 4.9 Skull and teeth of mammals 2 Mammalogy 4764 9/16/2009 Teeth and Dentition of Mammals Teeth Heterodont teeth with different functions Differentiated on the basis of function, resulting in increased One of the major keys efficiency acquiring and digesting food. to success of mammals Teeth occur in 3 bones of skull: Teeth of mammals are premaxilla, maxilla, dentary extremely variable with different diets -- more than other taxa Feldhamer et al.
    [Show full text]
  • Gondwana Vertebrate Faunas of India: Their Diversity and Intercontinental Relationships
    438 Article 438 by Saswati Bandyopadhyay1* and Sanghamitra Ray2 Gondwana Vertebrate Faunas of India: Their Diversity and Intercontinental Relationships 1Geological Studies Unit, Indian Statistical Institute, 203 B. T. Road, Kolkata 700108, India; email: [email protected] 2Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur 721302, India; email: [email protected] *Corresponding author (Received : 23/12/2018; Revised accepted : 11/09/2019) https://doi.org/10.18814/epiiugs/2020/020028 The twelve Gondwanan stratigraphic horizons of many extant lineages, producing highly diverse terrestrial vertebrates India have yielded varied vertebrate fossils. The oldest in the vacant niches created throughout the world due to the end- Permian extinction event. Diapsids diversified rapidly by the Middle fossil record is the Endothiodon-dominated multitaxic Triassic in to many communities of continental tetrapods, whereas Kundaram fauna, which correlates the Kundaram the non-mammalian synapsids became a minor components for the Formation with several other coeval Late Permian remainder of the Mesozoic Era. The Gondwana basins of peninsular horizons of South Africa, Zambia, Tanzania, India (Fig. 1A) aptly exemplify the diverse vertebrate faunas found Mozambique, Malawi, Madagascar and Brazil. The from the Late Palaeozoic and Mesozoic. During the last few decades much emphasis was given on explorations and excavations of Permian-Triassic transition in India is marked by vertebrate fossils in these basins which have yielded many new fossil distinct taxonomic shift and faunal characteristics and vertebrates, significant both in numbers and diversity of genera, and represented by small-sized holdover fauna of the providing information on their taphonomy, taxonomy, phylogeny, Early Triassic Panchet and Kamthi fauna.
    [Show full text]
  • Evolution of the Mammalian Fauces Region and the Origin of Suckling
    Evolution of the mammalian fauces region and the origin of suckling The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Citation Crompton, Alfred, Catherine Musinsky, Jose Bonaparte, Bhart- Anjan Bhullar, and Tomasz Owerkowicz. Evolution of the mammalian fauces region and the origin of suckling (2018). Citable link https://nrs.harvard.edu/URN-3:HUL.INSTREPOS:37364482 Terms of Use This article was downloaded from Harvard University’s DASH repository, and is made available under the terms and conditions applicable to Other Posted Material, as set forth at http:// nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of- use#LAA 1 Evolution of the mammalian fauces region and the origin of suckling Alfred Crompton1†, Catherine Musinsky1, Jose Bonaparte2, Bhart-Anjan Bhullar3, Tomasz Owerkowicz4 1: Harvard University, Organismic and Evolutionary Biology Department, Museum of Comparative Zoology, 26 Oxford St, Cambridge, MA 02138 USA 2: Museo Municipal de C. Naturales "C. Ameghino", 6600 MERCEDES – BS. AS. Argentina 3: Department of Geology & Geophysics, Yale University, PO Box 208109, New Haven, CT 06520- 8109 USA 4: Department of Biology, California State University in San Bernadino, 5500 University Pkwy, San Bernardino, CA 92407 USA †corresponding author: ORCID 0000-0001-6008-2587, [email protected], 617-495-3202 Acknowledgments Thanks to Dr. Edgar Allin for his comments on an early draft of this paper. Thanks to the Museum of Comparative Zoology, its Director, Professor James Hanken, and to the Center for Nanoscale Systems at Harvard University for providing the facilities and finances for this research.
    [Show full text]
  • The Role of Fossils in Interpreting the Development of the Karoo Basin
    Palaeon!. afr., 33,41-54 (1997) THE ROLE OF FOSSILS IN INTERPRETING THE DEVELOPMENT OF THE KAROO BASIN by P. J. Hancox· & B. S. Rubidge2 IGeology Department, University of the Witwatersrand, Private Bag 3, Wits 2050, South Africa 2Bernard Price Institute for Palaeontological Research, University of the Witwatersrand, Private Bag 3, Wits 2050, South Africa ABSTRACT The Permo-Carboniferous to Jurassic aged rocks oft1:J.e main Karoo Basin ofSouth Africa are world renowned for the wealth of synapsid reptile and early dinosaur fossils, which have allowed a ten-fold biostratigraphic subdivision ofthe Karoo Supergroup to be erected. The role offossils in interpreting the development of the Karoo Basin is not, however, restricted to biostratigraphic studies. Recent integrated sedimentological and palaeontological studies have helped in more precisely defming a number of problematical formational contacts within the Karoo Supergroup, as well as enhancing palaeoenvironmental reconstructions, and basin development models. KEYWORDS: Karoo Basin, Biostratigraphy, Palaeoenvironment, Basin Development. INTRODUCTION Invertebrate remains are important as indicators of The main Karoo Basin of South Africa preserves a facies genesis, including water temperature and salinity, retro-arc foreland basin fill (Cole 1992) deposited in as age indicators, and for their biostratigraphic potential. front of the actively rising Cape Fold Belt (CFB) in Fossil fish are relatively rare in the Karoo Supergroup, southwestern Gondwana. It is the deepest and but where present are useful indicators of gross stratigraphically most complete of several depositories palaeoenvironments (e.g. Keyser 1966) and also have of Permo-Carboniferous to Jurassic age in southern biostratigraphic potential (Jubb 1973; Bender et al. Africa and reflects changing depositional environments 1991).
    [Show full text]
  • A Non-Mammaliaform Cynodont from the Upper Triassic of South Africa: a Therapsid Lazarus Taxon?
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Wits Institutional Repository on DSPACE A non-mammaliaform cynodont from the Upper Triassic of South Africa: a therapsid Lazarus taxon? Fernando Abdala1*, Ross Damiani2, Adam Yates1 & Johann Neveling3 1Bernard Price Institute for Palaeontological Research, School of Geosciences, University of the Witwatersrand, Private Bag 3, WITS, 2050 South Africa 2Staatliches Museum für Naturkunde Stuttgart, Rosenstein 1, D-70191, Stuttgart, Germany 3Council for Geoscience, Private Bag X112, Pretoria, 0001 South Africa Received 20 January 2006. Accepted 10 January 2007 The tetrapod record of the ‘Stormberg Group’, including the Lower Elliot Formation, in the South African Karoo is widely dominated by archosaurian reptiles, contrasting with the therapsid dominion of the subjacent Beaufort Group. The only therapsids represented by skeletal remains in the Upper Triassic Lower Elliot Formation are the large traversodontid cynodont Scalenodontoides macrodontes and the recently described tritheledontid cynodont Elliotherium kersteni. Here we present a fragmentary lower jaw that provides evidence of a third type of cynodont for the Upper Triassic of South Africa. The fossil is tentatively assigned to the Diademodontidae. The latter representative of this family is known from the Late Anisian, and its tentative record in the Norian Lower Elliot Formation, if confirmed, will represent a case of Lazarus taxon. Thus, Diademodontidae apparently disappeared from the fossil record by the end of the Anisian and then reappeared in the Norian of South Africa, a stratigraphic interval of some 21 million years. This new cynodont record, together with the recently described Tritheledontidae, show that cynodonts are now the second most diverse tetrapod group in the Lower Elliot fauna.
    [Show full text]
  • Specimen Genus Articulated Skeleton?
    Raw data from Jasinoski and Abdala "Aggregations and parental care in the Early Triassic basal cynodonts Galesaurus planiceps and Thrinaxodon liorhinus " in PeerJ. Supplemental Table S1. Full list of Galesaurus planiceps and Thrinaxodon liorhinus specimens observed in this study. Specimen Genus Articulated Skeleton? AMMM 4283 Thrinaxodon Y AMMM 4284 Thrinaxodon N AMMM 5265 Thrinaxodon Y AMNH 2223 Galesaurus N AMNH 2227 Galesaurus N BP/1/1375 Thrinaxodon N BP/1/1376 Thrinaxodon N BP/1/1376a Thrinaxodon N BP/1/1693 Thrinaxodon Y BP/1/1730 Thrinaxodon Y BP/1/1737 Thrinaxodon Y BP/1/2513A Galesaurus Y BP/1/2513B Galesaurus N BP/1/2513C Galesaurus N BP/1/2776 Thrinaxodon Y BP/1/2793 Thrinaxodon N BP/1/2820 Thrinaxodon Y BP/1/2824 Thrinaxodon N BP/1/3848 Thrinaxodon N BP/1/3892 Galesaurus N BP/1/3911 Galesaurus Y BP/1/4263 Thrinaxodon N BP/1/4280 Thrinaxodon N BP/1/4282 Thrinaxodon Y BP/1/4331A Thrinaxodon N BP/1/4331B Thrinaxodon Y BP/1/4331C Thrinaxodon Y BP/1/4331D Thrinaxodon N BP/1/4506 Galesaurus Y BP/1/4597 Galesaurus N BP/1/4602 Galesaurus N BP/1/4637 Galesaurus Y BP/1/4714 Galesaurus N BP/1/472 Thrinaxodon Y BP/1/5064 Galesaurus N BP/1/5208 Thrinaxodon N BP/1/5372 Thrinaxodon Y BP/1/5905 Thrinaxodon Y BP/1/7199 Thrinaxodon Y BSP 1934 VIII506 Thrinaxodon N CM.01.2016 Thrinaxodon Y FMNH 156 Thrinaxodon Y FMNH PR 1774 Galesaurus N MCZ 8892 Thrinaxodon Y NHMUK 36220 Galesaurus N NHMUK R3731 Thrinaxodon N NHMUK R511 Thrinaxodon N NHMUK R511a Thrinaxodon N NHMUK R5480 Thrinaxodon N NMP 581 Galesaurus N NMQR 135 Galesaurus N NMQR 1416 Thrinaxodon
    [Show full text]
  • Osteohistology of Late Triassic Prozostrodontian Cynodonts from Brazil
    Osteohistology of Late Triassic prozostrodontian cynodonts from Brazil Jennifer Botha-Brink1,2, Marina Bento Soares3 and Agustín G. Martinelli3 1 Department of Karoo Palaeontology, National Museum, Bloemfontein, South Africa 2 Department of Zoology and Entomology, University of the Free State, Bloemfontein, South Africa 3 Departamento de Paleontologia e Estratigrafia, Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil ABSTRACT The Prozostrodontia includes a group of Late Triassic-Early Cretaceous eucynodonts plus the clade Mammaliaformes, in which Mammalia is nested. Analysing their growth patterns is thus important for understanding the evolution of mammalian life histories. Obtaining material for osteohistological analysis is difficult due to the rare and delicate nature of most of the prozostrodontian taxa, much of which comprises mostly of crania or sometimes even only teeth. Here we present a rare opportunity to observe the osteohistology of several postcranial elements of the basal prozostrodontid Prozostrodon brasiliensis, the tritheledontid Irajatherium hernandezi, and the brasilodontids Brasilodon quadrangularis and Brasilitherium riograndensis from the Late Triassic of Brazil (Santa Maria Supersequence). Prozostrodon and Irajatherium reveal similar growth patterns of rapid early growth with annual interruptions later in ontogeny. These interruptions are associated with wide zones of slow growing bone tissue. Brasilodon and Brasilitherium exhibit a mixture of woven-fibered bone tissue and slower growing parallel-fibered and lamellar bone. The slower growing bone tissues are present even during early ontogeny. The relatively slower growth in Brasilodon and Brasilitherium may be related to their small body size compared to Prozostrodon and Irajatherium. These brasilodontids also exhibit osteohistological similarities with the Late Triassic/Early Jurassic mammaliaform Morganucodon and the Late Cretaceous multituberculate mammals Kryptobaatar and Nemegtbaatar.
    [Show full text]
  • Gilles Cuny, a Late Triassic Cynodont from Holwell Quarries
    ORYCTOS, Vol. 5 : 69 - 73, Décembre 2004 A LATE TRIASSIC CYNODONT FROM HOLWELL QUARRIES (SOMERSET, ENGLAND) Gilles CUNY Geological Museum, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen K, Denmark Abstract : The presence of the dromatheriid cynodont Pseudotriconodon wildi is reported from the Rhaetian of Great Britain in the fissure deposits at Holwell Quarries. The British Rhaetic cynodont fauna, although consisting only of one dromatheriid tooth, one tooth of Tricuspes, and one tritylodontid fragmentary jaw, is similar to that found in the Germanic Realm. It appears to be the remnant of a fauna that covered all of Western Europe before the fragmentation of its habitat due to the Rhaetian transgression. Keywords : Cynodontia, Triassic, Rhaetian, Great Britain, Europe. Un cynodonte dans le Trias supérieur des carrières d’Holwell (Somerset, Angleterre) Résumé : La présence du cynodonte Pseudotriconodon wildi est signalée dans des remplissages de fissures rhétiens des carrières d’Holwell, en Angleterre. La faune de cynodontes du Rhétien d’Angleterre, bien que connue unique- ment d’après une dent de Dromatheriidés, une dent de Tricuspes, et un fragment de mâchoire de Tritylodontidés, est similaire à celle trouvée à la même époque en Europe continentale dans le bassin germanique. Il s’agit probablement des restes d’une faune plus ancienne qui couvrait l’ensemble de l’Europe avant que celle-ci ne soit fragmentée en plusieurs îles par la transgression rhétienne. Mots clés : Cynodontia, Trias, Rhétien, Europe, Grande-Bretagne. INTRODUCTION Moore (1859, 1861, 1862, 1864, 1867) was the first to study these fissures, set in quarries that are now The fissure fillings at Holwell quarries have closed.
    [Show full text]
  • Parental Care Or Opportunism in South African Triassic Cynodonts?
    Parental care or opportunism in South African AUTHOR: Triassic cynodonts? Julien Benoit1 AFFILIATION: In a paper published in Nature in 2018, Hoffman and Rowe1 describe the discovery of an adult tritylodontid cynodont, 1Evolutionary Studies Institute, Kayentatherium, from the Jurassic of the Kayenta Formation (Arizona, USA), accompanied by at least 38 perinatal School of Geosciences, University juveniles, all at the same very early stage of development. Such a high number of juveniles in one clutch is found of the Witwatersrand, Johannesburg, only in a handful of oviparous reptiles, and never in viviparous or ovoviviparous species1, suggesting that these South Africa cynodonts laid eggs. As tritylodontids are amongst the closest relatives to Mammaliaformes, and sometimes even reconstructed as their sister clade2, this textbook changing discovery implies that all non-mammaliaform CORRESPONDENCE TO: synapsids had an essentially reptilian-like reproductive biology1. Julien Benoit Hoffman and Rowe’s1 discovery forces a reappraisal of the interpretation of the rich fossil record of parental care EMAIL: in South African non-mammaliaform cynodonts3. [email protected] First, the implications of Hoffman and Rowe’s1 discovery for the evolution of parental care and lactation need to be discussed. With at least 38 hatchlings to feed, it can be safely assumed that lactation was not the main source of HOW TO CITE: Benoit J. Parental care or nutrients in Kayentatherium neonates (nor, by extension, in all more basal non-mammaliaform synapsids). Instead, opportunism in South African perinatal juveniles of Kayentatherium already had functional teeth despite their early age, which (1) impedes Triassic cynodonts? S Afr J Sci.
    [Show full text]